<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>注册页面</h1>
<form action="/reg">
    <!--@blue 给文本框添加失去焦点事件-->
  <input type="text" name="username" placeholder="用户名" @blur="check()">
  <span>{{info}}</span>
  <input type="text" name="password" placeholder="密码">
  <input type="submit" value="注册">

</form>
<!--引入CDN服务器的框架文件-->
<script src="https://cdn.bootcdn.net/ajax/libs/axios/0.21.1/axios.min.js"></script>
<script src="https://lf3-cdn-tos.bytecdntp.com/cdn/expire-1-M/vue/2.6.14/vue.js"></script>
<script>
  let v = new Vue({
    el:"form",
    data:{
      info:""
    },
    methods: {
        check:function () {
            let data = new FormData(document.querySelector("form"))
            //发请求检查用户名是否存在
            axios.post("/check",data).then(function (response){
                v.info= response.data;
            })
        }
      }
  })
</script>
</body>
</html>